Vacuum electric tube device



Dec. 8, 1931. R. w. LUNT 1,835,509

VACUUM ELECTRIC TUBE DEVICE Filed Jan. 22, 1926 WITNESSES INVENTOR Patented Dec. 8, 193i UNITED STATES PATENT OFFICE ROBERT WINSTANLEY LUNT, OF CHELSEA, LONDON IHTGLAND, ASSIGNOB TO WEST- INGHOUSE ELECTRIC & MANUFACTURING COMIPANY, A CORPORATION OF PENNSYL- VANLA Application filed January 22, 1926, Serial No. 82,991, and in Great Britain January 22, 1985.-

This invention relates to vacuum electric tube devices and more particularly to vacu um electric tubes having three or more electrodes used in the generation, amplification 6 or detection of alternating electric currents 10 the leads to the electrodes.

tage also arises in that the oscillatory current generated by the valve flows through the anode and grid leads necessitating lead-in wires and seals of high current carrying capacity which present difiiculties in manufacture and operation as will be well understood by those skilled in the art. It is consequently necessary to provide means whereby the seals are maintained cool during operation such as by directing on to the seals a current or blast 0 air.

According to the invention I provide within the envelope a conducting member which is in electrical connection or integral with the grid and displaced from it in the direction of its length, and I provide an external conducting member so related to the said internal member that a capacity is provided through which the oscillatory grid current may flow. In addition an external conducting member in some cases may be associated with the anode, surrounding either the anode itself or a conducting member displaced therefrom. Thus in the case of cylindrical electrodes the grid may be extended from one end in the direction of its length and connected to a cylindrical member which may be similar to the anode and may be of such diameter that it is near to the inner surface of the envelope. The external member may also comprise a cylinder surrounding the internal member. A similar external cylinder may be provided surrounding the anode.

Lead-in conductors sealed through the envelope may be provided whereby the anode ma be connected to a source of high tension an the grid connected to a source of potential for example through a biasing battery or a high resistance to the cathode.

When the anode is connected to a source of hi h tension through a choke coil such as to 0 er very hi h impedance to currents of the frequency 0 those enerated, and the grid is connected to the filament supply through a similar choke coil and a. high resistance, and the cathode is connected to its supply through similar choke coils, I find that if the external members associated with the anode and grid are connected through an inductance which may consist of the shortest possible connecting wire, the system generates oscillations of frequency which is determined principally by the dimensions of the system which comprises anode-external member associated therewith-connecting wire-external member associated with rid, and grid, and is only slightly influencef by the dimensions of the four choke coils mentioned, provided of course that the choke coils are so adjusted that the system does not oscillate in the absence of the wire connecting the external anode and grid members, an undesirable phenomenon which can be prevented by slightly varying the dimensions of one or more of the said chokes. These undesired oscillations have their frequency determined entirely by the constants of the four chokes,

and are easily distinguishable from the oscillations determined by the wire connecting the external members associated with anode and grid.

It will be understood that whilst the maximum obtainable frequency of. the generated oscillations is determined by the above characteristics, the circuit may be modified ina well known manner by the introduction of mductanee or capacity or both so that oscillations of desired frequency lower than the maximum may be obtained.

To enable the invention to be clearly understood it will now be described with reference to the accompanying drawings in which the two figures are lon itudinal sections of two forms of vacuum e ectric tube device in accordance with the invention.

Referring to Fig. 1 of the drawings, 1 is the evacuated containin vessel, which may be of hard glass or si we. provided at its ends with re-entrant tubes 2 and 3'respectively. 4 is a filament cathode having lead-in conductors 5 supported in the pinch or seal 6 of the re-entrant tube 3 and connected with external conductors 7 The filament 4 is maintained in tension by means of a spring 8 connected to a support 9 also carried by the seal 6. The grid 10 is rigidly supported by members 11 from a conducting member 12 which is longitudinally displaced from the 'd 10 and which is shown as a hollow cylini'. The member 12 is ri 'dly su ported from the re-entrant tube 3 y mem rs 13 and a clamp 14. A lead-in wire 15 passing through the seal 6 is connected to the member 12 as shown.

A cylindrical anode 16 surrounding the filament 4 and grid 10 is mounted by means of members 17 and a clamp 18 upon the reentrant tube 2 and is connected with a lead-in wire 19 which passes through a inch or seal 20 upon the re-entrant tube 2. 1 may be evacuated to a high degree through the tubulation 21.

Cylindrical members 22 and 23 external to the envelope 1 surround the grid and anode respectively. The members 22 and 23 may be connected to one another by means of an inductance which may be in the form of a coil or may be constitutedby a straight wire 2! which in the limit may be the shortest possible conductor connectlng the members.

With the arrangement above described, oscillations will be generated when the anode lead 19, grid lead 15, and the filament leads 7 are connected to sources of steady potential through hi h uency choke coils (not shown). e an e lead 19 and the grid lead 15 may be coiled into helices within the envelope so that the necessity for adding choke coils is avoided, also the small charging current which must otherwise flow through the anode and 'd seals to charge the leads thereof being fi e reby avoided.

Referring to Fig. 2, wherein similar ref-- erence numerals are applied to similar parts where possible, only one re-entrant tube 25 is provided; The filament cathode 4' may be supported in a manner similar to that shown in Fig. 1. The id 10 forms a lon tudinal extension of a ollow metal cylimfe r 26 which surrounds and may be supported by the re-entrant tube 25.

The anode 16 is extended longitudinally and supported within the envelope 1 by any suitable means (not shown) and has connected to it the lead-in wire 19 which passes through a seal 20 in the wallof the envelope. The conducting member "2 2 by means of which capacity coupling with the grid extension 26 is efi'ected," 15; located as shown within the re-entrant tube 25. The conducthe envelope ing member 23, by means of which capacity coupling with the anode is eflected, is located outside the envelope 1 surrounding the left-hand end or extension of the anode 16. The members 22 and 23 may be connected together by means of a coil or the conductor 24 in the manner already described in connection with Fig. 1.

Oscillating triodes such as above described may be utilized for wireless transmission at very short wave lengths. A tuned aerial circuit may be coupled, for example capacitatively or inductively, to the osc1llatory circuits herein described. The triodes however may be used to supply energy for other purposes than wireless transmission. Moreover, the invention is not limited in its application to the generation of oscillations.

The extension of the grid and the consequent distance between the exterior conducting members should be made sufiiciently great to prevent arc-over between them. The external members such as the metal cylinders may be arranged closely to fit the envelope, that is to say, substantially in contact with its surface or they may be of larger (or smaller) diameter than the diameter of the envelope so as to be spaced from the surface thereof. Provision may be made for artificially cooling the external members, such as by the circulation of water or other cooling fluid in contact therewith, by which means heat dissipated at the anode can be absorbed and for increasing the proportion of the radiant heat from the anode absorbed by the associated external member by coating the surface adjacent the envelope with a material of low emissivity such as lamp black.

The surface of the grid member may be similarly coated.

I claim as my invention i 1. In combination with a vacuum-type container enclosing a cathode, an anode and a control electrode, a conducting surface connected with said control electrode, a conducting member external to said container in proximit to said conducting surface, a second con ucting member external to said con-,

tainer in proximity to said anode and means for interconnecting said two conducting members.

2. In combination with a vacuum-type container enclosing a cathode, an anode and a control electrode, a conducting surface connected with said control electrode, a conducting member external to said container in proximity to said conducting surface, a second conducting member external to said container in proximity to the anode, a. substantially straight conductor for interconnecting said two conducting members.

- 3. In combination with a vacuum-type container enclosing a cathode, an anode and a control electrode, a conducting surface connected with said control electrode-and distainer in proximity to said conducting surface and capacitatively coupled to said anode.

5. In combination with a vacuum-type container enclosing a cathode, an anode and a control electrode, a conducting surface connected with said control electrode and dis placed longitudinally therefrom, a conducting member external to said container in proximity to said conducting surface, a second conducting member external to said container in proximity to said anode, and means for interconnecting said two conducting members.

6. In combination with a. vacuum-type container enclosing a cathode, a cylindrical anode, a control electrode and a conducting sheet connected with said control electrode and displaced longitudinally of the tube therefrom, a conducting member external to said container in proximity to said conducting sheet and capacitatively coupled to said anode.

7. A device for generating high-frequency electrical oscillations comprising an evacuated container enclosing a cathode, a control-electrode and an anode, and means external of said container electrostatically coupling said control-electrode and said anode, said means being entirely free from metallic connections extending through the wall of said container.

8. A device for generating high-frequency electrical oscillations comprising an evacuated container enclosing a cathode, a control-electrode and an anode, means extending through a wall of said container for supplying potential to said anode, and means entirely distinct from said potential-supply means for electrostatically coupling said control-electrode and said anode said means being entirely free from metallic connections extending through the wall of said container 9. A device for generating high-frequency electrical oscillations comprising an evacuated container enclosing a cathode, a; controlelectrode and an anode, means extending through a wall of said container for supplying potential to said anode, additional means extending through a wall of said container for supplying potential to said cathode, and means external of said container and entirely free of conductive connections extending through any wall of said container for electrostatically coupling said control-electrode and said anode.

In testimony whereof I have hereunto subscribed my name this thirty-first day of December, 1925.

ROBERT WINSTANLEY LUNT. 

